Statue

The statue is a notably recurring object in each of the chapters of GRIS. The statue is likely to represent the mother of Gris.

Given that the story of the game is that Gris is grieving over her mother. In the secret ending (after finding all of the mementos), the scene happens in the lowest area in the game, as well as in the area representing depression, the black creature, symbolizing the pain and suffering Gris is going through, breaking the statue likely means something along the lines of. She is hurting so much, that she is beginning to forget about the good memories of her mother, and is being swallowed by the "why does it even matter anymore" mindset of depression. It is only after escaping, and coming to terms with her loss, that the statue is fixed and she is able to ascend higher and end the game, representing acceptance.